Firing mechanism for a cartridge firing device

ABSTRACT

The firing mechanism comprises a hammer and a trigger which are pivotally mounted at spaced points and have relatively approaching portions defining a multipointed cam connection therebetween, the points of which are relatively engageable and disengageable with and from one another when the hammer and trigger undergo rotation with respect to a line through the pivot points thereof. The mechanism also comprises an elongated yieldable biasing means which is interconnected at its ends with the hammer and the trigger on one side of the line. The bias of the biasing means is yieldable intermediate the ends thereof when the points of the cam connection are relatively engaged with one another and a force is applied to one of the hammer and the trigger to rotate the points in the direction relatively away from the line on the other side thereof. However, when a force is applied to the trigger to relatively disengage the points from one another on the other side of the line, the bias is operable firstly, to rotate the hammer into its firing position, and thence, when the latter force is discontinued, to rotate the trigger into the at-rest position thereof.

United States Patent Dirstine FIRING MECHANISM FOR A CARTRIDGE FIRINGDEVICE John T. Dirstine, Evergreen State College, Apt. M-302B, Olympia,Wash. 98505 221 Filed: June 18,1973

[2i] Appl. No; 371,264

[76] Inventor:

Primary ExaminerBenjamin A. Borchelt Assistant Examiner-C. T. JordanAttorney, Agent, or FirmChristensen, OConnor, Garrison & Havelka Sept.9, 1975 [57] ABSTRACT The firing mechanism comprises a hammer and atrigger which are pivotally mounted at spaced points and have relativelyapproaching portions defining a multipointed cam connectiontherebetween, the points of which are relatively engageable anddisengageable with and from one another when the hammer and triggerundergo rotation with respect to a line through the pivot pointsthereof. The mechanism also comprises an elongated yieldable biasingmeans which is interconnected at its ends with the hammer and thetrigger on one side of the line. The bias of the biasing means isyieldable intermediate the ends thereof when the points of the camconnection are relatively engaged with one another and a force isapplied to one of the hammer and the trigger to rotate the points in thedirection relatively away from the line on the other side thereof.However, when a force is applied to the trigger to relatively disengagethe points from one another on the other side of the line, the bias isoperable firstly, to rotate the hammer into its firing position, andthence, when the latter force is discontinued, to rotate the triggerinto the at-rest position thereof.

4 Claims, 6 Drawing Figures FIRING MECHANISM FOR A CARTRIDGE FIRINGDEVICE BACKGROUND FOR THE INVENTION This invention relates to cartridgefiring devices, and in particular, to a trigger-actuated firingmechanism for such devices. In prior art mechanisms of this nature, thefunctions of propelling the hammer against the cartridge and returningthe trigger to its at-rest position are performed by two or moresprings, both of which are heavily pretensioned. According to thepresent invention, both functions are performed by a single spring orspring-like biasing means, and the biasing means is incorporated intothe mechanism in such a way that it requires very little pretensioning,relative to the prior art. As a result, the trigger can be operated withconsiderably less pull than was necessary in the devices of the priorart, as well as with a pull which is substantially linear. Both of thesefeatures contribute significantly to firing accuracy, since it is wellknown that the act of tightening the hand, finger and forearm muscles topull a trigger, can effectively move the gun off target, particularlywhere the trigger pull must be accentuated to overcome spring resistancein the trigger, and/or requires a non-linear force because of springreaction in the firing mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be best understoodby reference to the accompanying drawings which illustrate a presentlypreferred embodiment of the firing mechanism as it is employed in arevolver.

In the drawings,

FIG. 1 is a part-removed, part cross-sectional side elevational view ofthe revolver showing the firing mechanism in the at-rest conditionthereof;

FIG. 2 is another such view of the revolver showing the firing mechanismin the partially cocked condition;

FIG. 3 is a third such view of the revolver showing the firing mechanismin the fully cocked condition of the single action mode of operating thesame, or alternatively, in a transitory stage of the double-action modeof operating the same;

FIG. 4 is a fourth such view of the revolver showing the firingmechanism in the firing condition;

FIG. 5 is a fifth such view of the revolver showing the mode by whichthe firing mechanism reassumes the rest condition from the firingcondition of FIG. 4; and

FIG. 6 is a graph illustrating the trigger pull characteristics of therevolver vis a vis those of prior art revolvers.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, itwill be seen that the revolver 2 is basically a Model 19 Smith andWesson Double Action Revolver, and accordingly, is capable of operatingeither in a single action mode in which the hammer 4 is manually cockedbefore the trigger 6 is pulled to release the hammer for firing, or in adouble action mode in which the hammer is both cocked and released forfiring through pull of the trigger alone. In each case, the firingsequence takes place when the hammer is cocked to the condition of FIG.3, and then released so as to strike one of a plurality of cartridges 8received in a rotatable cylinder I mounted behind the barrel 12 of therevolver. Moreover, in each case,

the sequence employs a firing mechanism 14 which includes not only thehammer and the trigger, but also a three-pointed cam connection 16therebetween, the points 18, 20 and 22 of which are relativelyengageable and disengageable with and from one another when the hammerand trigger undergo rotation with respect to a line through the pivotpins 24 and 26 thereof. As seen, the hammer and the trigger haverelatively approaching portions 28 and 30 interposed between the pins 24and 26 thereof, and the undersides 32 and 34 of the portions are planar.As the hammer portion 28 approaches the point of maximum convergencewith the trigger, it takes the form of a finger 18 which protrudesbeyond the forward face 36 of the hammer, adjacent the underside 32 ofthe portion. Similarly, as the trigger portion 30 approaches the pointof maximum convergence with the hammer, it also assumes the form of afinger 20, although in this instance the finger 20 is separated from theunderside 34 of the trigger portion by a recess 38 which is deeply insetinto the trigger portion 30 and disposed to lie opposite the finger 18of the hammer in the at-rest condition of the mechanism in FIG. I. Thetrig ger portion 30 also has a recess or swale 40 in the upper sidethereof, which is adapted to enable the trigger portion to be swung intoa closer relationship with the cyl inder, as in FIG. 4. The fingers 18and 20 constitute two points of the cam connection 16 and operate as aknee joint between the trigger and the hammer in the first stage of thesingle action mode of the mechanism 14. In the double action mode,however, the finger 20 of the trigger cooperates with a lever 42 whichis pivotally connected with the hammer in a position in which it isdisposed behind and abreast of the hammer in the drawings. The upper endof the lever is loaded against a stop 44 on the backside of the hammerby means of a spring 46 interposed between the hammer and the lower end22 of the lever. In the stopped condition, the lower end of the lever isinclined outboard of the forward face 36 of the hammer, and is disposedslightly above the finger 18 of the hammer so as to leave a deeply insetrecess 48 therebetween. This recess is adapted to accommodate the finger20 of the trigger, so that when the mechanism is operated between thecondition of FIG. 1 and the condition of FIG. 2, the finger 20 of thetrigger bears against the rounded lower end 22 of the lever 42. Ofcourse, the lever in turn bears against the stop 44, so that a turningmoment is applied to the hammer. Ultimately, however, the finger 20escapes from the recess 48 as the mechanism moves from the condition ofFIG. 2 to the condition of FIG. 4. On the other hand, when the mechanismmoves between the condition of FIG. 5 and the condition of FIG. I, thefinger 20 is able to reenter the recess 48 by displacing the lever 42 inthe clockwise direction against the bias of the spring 46.

The motions referred to above are effected in part against, and in partwith the aid of a coiled spring 50 caged between the hammer and thetrigger. As seen, other portions 52 and 54 of the hammer and the triggerdepend from the same at the remote ends of the planar undersides 32 and34 of the members, and these portions are mutually opposed to oneanother when the mechanism is in the condition of FIG. I. The dependingportion 54 of the trigger has a cup-shaped recess 56 therein, whereasthe depending portion 52 of the hammer has an oblique-angled slot 58therethrough. The spring 50 is caged about a rod 60, one end of whichhas a flanged cap 62 thereon which is accommodated in the recess 56 ofthe trigger portion 54. The other end 60' of the rod is inserted in theslot 58 and has a washer 64 slidably engaged thereon which is trappedbetween the spring and the depending portion 52 of the hammer to serveas a compression flange for the spring.

In the at-rest condition of FIG. 1, the fingers l8 and 20 of therelatively approaching portions 28 and 30 of the hammer and the triggerare disposed below the line between the pivot points 24 and 26 of themembers, and the hammer and the trigger are biased by the spring 50 inthe clockwise and counterclockwise directions, respectively, there beinga stop 66 for the trigger below the cylinder, and a stop (not shown) forthe hammer at the rear end of the cylinder. When a counterdirectionalforce is applied to either the hammer or the trigger, the finger 20 iseither engaged with the end 22 of the lever 42, or is engaged by thefinger 18, thus dictating that the members will rotate together, butcounterdirectionally, toward the line between the points 24 and 26.Moreover, the spring 50 is compressed between the depending portions 52and 54 of the hammer and the trigger, as seen in FIG. 2. Ultimately, thefingers l8 and 20 move to the upper side of the line, and in the singleaction mode of the mechanism, the hammer assumes a cocked condition, andremains in this condition until it is disturbed by the application of anew force to the trigger. See FIG. 3. When such a force is applied, orwhen a trigger force is applied and continued as in the case of thedouble action mode of operation, then the finger 20 is driven in theclockwise direction out of the recess 48 so as to escape the connection16 entirely. At the same time, the hammer is released to operate againsta cartridge 8 under the bias of the spring 50. See FIG. 4. Subsequently,when the trigger force is discontinued, the energy remaining in thespring 50 is employed to return the trigger to its at-rest condition ofFIG. 1, and as explained earlier, the trigger finger 20 reenters therecess 48 by depressing the lever 42 against the spring 46. See FIG. 5.

During the latter operation, moreover, a pawl 68 operates to rotate thecylinder in conventional fashion.

In summary then, the spring 50 provides the necessary energy for allphases of the firing operation, including firing and trigger return.Moreover, due to the nature and disposition of the spring, the pullwhich must be exerted on the trigger is considerably less than wasnecessary with the multiple spring assemblies employed in the prior art.Also, because of the nature and disposition of the spring, the pull issubstantially linear.

The pull is contrasted with the prior art in FIG. 6. The dashed linerepresents the trigger pull necessary for a conventional firingmechanism; the solid line represents that necessary for the mechanism ofthe present invention. With the conventional mechanism, it will be notedthat the initial pull necessary to overcome the static resistance of thehammer spring at T, is often as high as twelve pounds, and that afterthe initial pull, a nonlinear pull of as high as sixteen pounds isnecessary to achieve firing at T On the other hand, in the case of thepresent invention, the initial pull necessary to overcome the staticresistance of the coil spring 50, is normally only a maximum of twopounds at T and thereafter firing is effected at T with a substantiallylinear pull of no more than seven pounds.

1 claim:

1. in a cartridge firing device, a firing mechanism comprising a hammerand a trigger pivotally mounted at spaced points and having portionsthereof which relatively approach one another and define a multipointedcam connection therebetween, the points of which cam connection arerelatively engageable and disengageable with and from one another whenthe hammer and the trigger undergo rotation with respect to a linethrough the pivot points thereof, and also having portions thereof whichin general are mutually opposed to one another on one side of the linewhen the hammer and trigger are in the firing and at-rest positionsthereof, respectively, an elongated rod, the respective end portions ofwhich are pivotally connected with the mutually opposing portions of thehammer and the trigger at points spaced apart from the line through thepivot points of the hammer and the trigger, said rod being telescopicrelative to the mutually opposing portions of the hammer and thetrigger, and a coiled spring which is caged by the rod between themutually opposing portions of the hammer and the trigger, so as to yieldintermediate the ends of the rod when the points of the cam connectionare relatively engaged with one another and a force is applied to one ofthe hammer and the trigger to rotate the points of the cam connection inthe direction relatively away from the line on the other side thereof,and so as to rotate the hammer into its firing position when a force isapplied to the trigger to relatively disengage the points of the camconnection from one another on the other side of the line, and then torotate the trigger into the at-rest position thereof when the latterforce is discontinued.

2. The cartridge firing device according to claim 1 wherein the pointsof the cam connection relatively engage one another on the one side ofthe line when the hammer and the trigger are in the firing and atrestpositions thereof, respectively.

3. The cartridge firing device according to claim 1 wherein the onemutually opposing portion has an oblique angled slot therethrough, andthe one end portion of the rod is inserted in the slot and slidablyengaged with the one mutually opposing portion at the mouth of the slot,there being a washer-like element slidably engaged on the rod betweenthe spring and the one mutually opposing portion at the mouth of theslot.

4. The cartridge firing device according to claim 3 wherein the othermutually opposing portion has a cup shaped recess therein, and the otherend portion of the rod has a flanged cap thereon which is pivotallyengaged in the recess, with the spring bearing against the flangethereof.

i It i i

1. In a cartridge firing device, a firing mechanism comprising a hammerand a trigger pivotally mounted at spaced points and having portionsthereof which relatively approach one another and define a multi-pointedcam connection therebetween, the points of which cam connection arerelatively engageable and disengageable with and from one another whenthe hammer and the trigger undergo rotation with respect to a linethrough the pivot points thereof, and also having portions thereof whichin general are mutually opposed to one another on one side of the linewhen the hammer and trigger are in the firing and at-rest positionsthereof, respectively, an elongated rod, the respective end portions ofwhich are pivotally connected with the mutually opposing portions of thehammer and the trigger at points spaced apart from the line through thepivot points of the hammer and the trigger, said rod being telescopicrelative to the mutually opposing portions of the hammer and thetrigger, and a coiled spring which is caged by the rod between themutually opposing portions of the hammer and the trigger, so as to yieldintermediate the ends of the rod when the points of the cam connectionare relatively engaged with one another and a force is applied to one ofthe hammer and the trigger to rotate the points of the cam connection inthe direction relatively away from the line on the other side thereof,and so as to rotate the hammer into its firing position when a force isapplied to the trigger to relatively disengage the points of the camconnection from one another on the other side of the line, and then torotate the trigger into the at-rest position thereof when the latterforce is discontinued.
 2. The cartridge firing device according to claim1 wherein the points of the cam connection relatively engage one anotheron the one side of the line when the hammer and the trigger are in thefiring and atrest positions thereof, respectively.
 3. The cartridgefiring device according to claim 1 wherein the one mutually opposingportion has an oblique angled slot therethrough, and the one end portionof the rod is inserted in the slot and slidably engaged with the onemutually opposing portion at the mouth of the slot, there being awasher-like element slidably engaged on the rod between the spring andthe one mutually opposing portion at the mouth of the slot.
 4. Thecartridge firing device according to claim 3 wherein the other mutuallyopposing portion has a cup shaped recess therein, and the other endportion of the rod has a flanged cap thereon which is pivotally engagedin the recess, with the spring bearing against the flange thereof.